(a) Explain the function of a moderator in a thermal nuclear reactor with reference to the concept of neutron economy.
(b) Describe how the insertion of control rods alters the effective multiplication factor k of the reactor core. Indicate whether k increases or decreases and why.
(c) A reactor is operating steadily at k=1.02. Predict qualitatively how the reactor power will change if no corrective action is taken. State how appropriate movement of the control rods can restore the reactor to a critical state.